Many Serv-U Listeners Results In Small CPU Spikes - KB Article #1770

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Serv-U allows for the creation of many independent "Listeners", each of which allows incoming connections to be made to Serv-U. In some unique cases, administrators may find it necessary to create a very large number of listeners to meet their needs. In cases like these, Serv-U will exhibit small, cyclic spikes in CPU usage which do not impact server performance or consume excessive system resources. These spikes are indicative of tasks Serv-U runs continually to optimize its use of resources and CPU time.

For an example of typical CPU usage on a system with 255 explicitly defined FTP listeners, see below:

Newer versions of Serv-U reduce the regularly scheduled operations so that if hundreds of listeners are configured, they are only initialized once when the server is started to avoid CPU spikes over time.